If the price of a commodity be raised by 10%, find out by how much per cent must a householder reduce his consumption of that commodity, so as not to increase his expenditure.

Correct option is B

Given:
The price of the commodity be raised by 10%.
Solution:
Let the price of 100 units of the commodity be Rs. 100.
After raise, the price of 100 units of the commodity = 100 + 100 × 10%
=> Rs. 110
At Rs. 100, the amount of commodity that can be purchased
=> 100/110 × 100
=> 1000/11 units
Now, consumption reduction% =

By 

householder must reduce his consumption of that commodity, so as not to increase his expenditure.